Using Autodesk Inventor, I created a small 1.5 inch cube, which I exported as a .CTL and uploaded to this site. The cube was a test intended to verify that this service would work, before actually investing time to make a useful model. The cube showed up fine, except the scale was off. 1.5 inches turned into 3.8. Is this a known/common issue? What can I do to fix this?

Thank you for your assistance! I'm looking forward to making awesome things.
wes_ismore